export const GPS = () => {
  return {
    PI: 3.14159265358979324,
    x_pi: 3.14159265358979324 * 3000.0 / 180.0
  }
}
export const outOfChina = (lat, lon) => {
  if (lon < 72.004 || lon > 137.8347) { return true }
  if (lat < 0.8293 || lat > 55.8271) { return true }
  return false
}
export const transformLat = (x, y) => {
  var PI = 3.14159265358979324
  // var x_pi = 3.14159265358979324 * 3000.0 / 180.0
  var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x))
  ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0
  ret += (20.0 * Math.sin(y * PI) + 40.0 * Math.sin(y / 3.0 * PI)) * 2.0 / 3.0
  ret += (160.0 * Math.sin(y / 12.0 * PI) + 320 * Math.sin(y * PI / 30.0)) * 2.0 / 3.0
  return ret
}
export const transformLon = (x, y) => {
  var PI = 3.14159265358979324
  // var x_pi = 3.14159265358979324 * 3000.0 / 180.0
  var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x))
  ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0
  ret += (20.0 * Math.sin(x * PI) + 40.0 * Math.sin(x / 3.0 * PI)) * 2.0 / 3.0
  ret += (150.0 * Math.sin(x / 12.0 * PI) + 300.0 * Math.sin(x / 30.0 * PI)) * 2.0 / 3.0
  return ret
}
export const delta = (lat, lon) => {
  var PI = 3.14159265358979324
  // var x_pi = 3.14159265358979324 * 3000.0 / 180.0
  // Krasovsky 1940
  //
  // a = 6378245.0, 1/f = 298.3
  // b = a * (1 - f)
  // ee = (a^2 - b^2) / a^2;
  var a = 6378245.0 //  a: 卫星椭球坐标投影到平面地图坐标系的投影因子。
  var ee = 0.00669342162296594323 //  ee: 椭球的偏心率。
  var dLat = transformLat(lon - 105.0, lat - 35.0)
  var dLon = transformLon(lon - 105.0, lat - 35.0)
  var radLat = lat / 180.0 * PI
  var magic = Math.sin(radLat)
  magic = 1 - ee * magic * magic
  var sqrtMagic = Math.sqrt(magic)
  dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * PI)
  dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * PI)
  return { 'lat': dLat, 'lon': dLon }
}
// WGS-84 to GCJ-02
export const gcj_encrypt = (wgsLat, wgsLon) => {
  if (this.outOfChina(wgsLat, wgsLon)) { return { 'lat': wgsLat, 'lon': wgsLon } }

  var d = this.delta(wgsLat, wgsLon)
  return { 'lat': wgsLat + d.lat, 'lon': wgsLon + d.lon }
}
export const toTmapLatLng = (wgsLat, wgsLon) => {
  if (outOfChina(wgsLat, wgsLon)) { return { 'lat': wgsLat, 'lon': wgsLon } }
  var d = delta(wgsLat, wgsLon)
  return new AMap.LngLat(parseFloat(wgsLon) + parseFloat(d.lon), parseFloat(wgsLat) + parseFloat(d.lat))
}
// GCJ-02 to WGS-84
export const gcj_decrypt = (gcjLat, gcjLon) => {
  if (this.outOfChina(gcjLat, gcjLon)) { return { 'lat': gcjLat, 'lon': gcjLon } }

  var d = this.delta(gcjLat, gcjLon)
  return { 'lat': gcjLat - d.lat, 'lon': gcjLon - d.lon }
}
// GCJ-02 to WGS-84 exactly
// export const gcj_decrypt_exact = (gcjLat, gcjLon) => {
//   var initDelta = 0.01
//   var threshold = 0.000000001
//   var dLat = initDelta, dLon = initDelta
//   var mLat = gcjLat - dLat, mLon = gcjLon - dLon
//   var pLat = gcjLat + dLat, pLon = gcjLon + dLon
//   var wgsLat, wgsLon, i = 0
//   while (1) {
//     wgsLat = (mLat + pLat) / 2
//     wgsLon = (mLon + pLon) / 2
//     var tmp = this.gcj_encrypt(wgsLat, wgsLon)
//     dLat = tmp.lat - gcjLat
//     dLon = tmp.lon - gcjLon
//     if ((Math.abs(dLat) < threshold) && (Math.abs(dLon) < threshold)) { break }
//
//     if (dLat > 0) pLat = wgsLat; else mLat = wgsLat
//     if (dLon > 0) pLon = wgsLon; else mLon = wgsLon
//
//     if (++i > 10000) break
//   }
//   // console.log(i);
//   return { 'lat': wgsLat, 'lon': wgsLon }
// }
// GCJ-02 to BD-09
// export const bd_encrypt = (gcjLat, gcjLon) => {
//   var x = gcjLon, y = gcjLat
//   var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * this.x_pi)
//   var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * this.x_pi)
//   bdLon = z * Math.cos(theta) + 0.0065
//   bdLat = z * Math.sin(theta) + 0.006
//   return { 'lat': bdLat, 'lon': bdLon }
// }
// BD-09 to GCJ-02
// export const bd_decrypt = (bdLat, bdLon) => {
//   var x = bdLon - 0.0065, y = bdLat - 0.006
//   var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * this.x_pi)
//   var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * this.x_pi)
//   var gcjLon = z * Math.cos(theta)
//   var gcjLat = z * Math.sin(theta)
//   return { 'lat': gcjLat, 'lon': gcjLon }
// }
// WGS-84 to Web mercator
// mercatorLat -> y mercatorLon -> x
export const mercator_encrypt = (wgsLat, wgsLon) => {
  var x = wgsLon * 20037508.34 / 180.0
  var y = Math.log(Math.tan((90.0 + wgsLat) * this.PI / 360.0)) / (this.PI / 180.0)
  y = y * 20037508.34 / 180.0
  return { 'lat': y, 'lon': x }
  /*
  if ((Math.abs(wgsLon) > 180 || Math.abs(wgsLat) > 90))
      return null;
  var x = 6378137.0 * wgsLon * 0.017453292519943295;
  var a = wgsLat * 0.017453292519943295;
  var y = 3189068.5 * Math.log((1.0 + Math.sin(a)) / (1.0 - Math.sin(a)));
  return {'lat' : y, 'lon' : x};
  // */
}
// Web mercator to WGS-84
// mercatorLat -> y mercatorLon -> x
export const mercator_decrypt = (mercatorLat, mercatorLon) => {
  var x = mercatorLon / 20037508.34 * 180.0
  var y = mercatorLat / 20037508.34 * 180.0
  y = 180 / this.PI * (2 * Math.atan(Math.exp(y * this.PI / 180.0)) - this.PI / 2)
  return { 'lat': y, 'lon': x }
  /*
  if (Math.abs(mercatorLon) < 180 && Math.abs(mercatorLat) < 90)
      return null;
  if ((Math.abs(mercatorLon) > 20037508.3427892) || (Math.abs(mercatorLat) > 20037508.3427892))
      return null;
  var a = mercatorLon / 6378137.0 * 57.295779513082323;
  var x = a - (Math.floor(((a + 180.0) / 360.0)) * 360.0);
  var y = (1.5707963267948966 - (2.0 * Math.atan(Math.exp((-1.0 * mercatorLat) / 6378137.0)))) * 57.295779513082323;
  return {'lat' : y, 'lon' : x};
  // */
}
// two point's distance
export const distance = (latA, lonA, latB, lonB) => {
  var earthR = 6371000.0
  var x = Math.cos(latA * this.PI / 180.0) * Math.cos(latB * this.PI / 180.0) * Math.cos((lonA - lonB) * this.PI / 180)
  var y = Math.sin(latA * this.PI / 180.0) * Math.sin(latB * this.PI / 180.0)
  var s = x + y
  if (s > 1) s = 1
  if (s < -1) s = -1
  var alpha = Math.acos(s)
  var distance = alpha * earthR
  return distance
}
